Production method of anisotropic conductive connector

ABSTRACT

The present invention aims at providing a production method capable of efficiently producing an anisotropic conductive connector having a structure wherein the center line of plural conductive paths penetrating in the thickness direction of a film substrate forms an angle with a line perpendicular to the principal plane of the film substrate, which shows high reliability of connection with the target. The present invention is characterized in that an insulating film and a conductive wire are integrated on a core, the resulting roll-like product is removed from the core, which is opened to give a plane-like product, plural films with conductive wires 10A are cut out from the plane-like product, then the plural films with conductive wires are accumulated such that the conductive wires  2  of the adjacent films are in parallel relation with each other, the obtained laminate is heated and pressurized and the obtained block is cut in a predetermined film thickness along the plane forming an angle with the conductive wire  2.

TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to a production method of ananisotropic conductive connector. More particularly, the presentinvention relates to a production method of an anisotropic conductiveconnector having a structure wherein a conductive path penetrating inthe thickness direction of a film substrate has an inclination.

BACKGROUND OF THE INVENTION

[0002] For an electrical connection between an electronic component suchas a semiconductor element (IC chip) and the like and a circuit board,an anisotropic conductive connector has been widely used in recentyears. As an anisotropic conductive connector, one prepared bydispersing conductive fine particles in an insulating film has beenconventionally known. This anisotropic conductive connector isassociated with problems of structurally difficult connection with aconnection target having a fine pitch and the need for forming aterminal of the target, such as electrode of semiconductor element andthe like in a protrusion (bump). Thus, as an anisotropic conductiveconnector capable of resolving such problems, namely, an anisotropicconductive connector capable of dealing with finely pitched and bumplesstarget, the Applicant of this invention has proposed an anisotropicconductive connector (film) comprising, in the substrate of aninsulating film, plural conductive paths penetrating in the thicknessdirection of the film substrate while being insulated from each other,in international publication WO98/07216 (U.S. Pat. No. 6,245,175).

[0003] Generally, anisotropic conductive connectors are being used forthe following two uses. One is use for, what is called, mountingconnectors, wherein an anisotropic conductive connector is disposedbetween an electronic component such as a semiconductor element and thelike and a circuit board, which, upon heating and pressurizing,electrically and mechanically connects the electronic component and thecircuit board. The other is use as, what is called, a test connector,wherein, in functional tests of electronic components such assemiconductor element and the like, an anisotropic conductive connectoris inserted between an electronic component and a circuit board, which,upon press adhesion to the both, achieves a functionally testableconduction between the electronic component and the circuit board.

[0004] The use of an anisotropic conductive connector as a testconnector is necessary because a functional test of an electroniccomponent after mounting the electronic component on a circuit board toprove the electronic component to be defective results in disposal of agood circuit board together with the component, thereby lowering theproduction efficiency of the circuit board and increasing an economicalloss.

[0005] In a test of electronic component such as semiconductor elementand the like, damage of terminal and deformation of the terminal areprevented only when an anisotropic conductive connector is brought intocontact with an electronic component and a circuit board at a lowerpressure. The Applicant has proposed, in the above-mentionedinternational publication WO98/07216, an anisotropic conductiveconnector having a structure wherein plural conductive paths penetratinga film substrate in the thickness direction thereof are disposed suchthat the center line thereof form an angle with the line perpendicularto the principal plane of the film substrate. In other words, byimparting an inclination in a given direction to plural conductive pathspenetrating in the thickness direction of a film substrate, theconductive path bends and the pressure applied on the electroniccomponent and circuit board is decreased, when an electronic componentis placed on the circuit board via an anisotropic conductive connectorand the electronic component is pressed from above.

[0006] Such anisotropic conductive connector has been conventionallymanufactured according to the method described in the above-mentionedinternational publication WO98/07216. To be specific, an insulatedconductive wire (metal wire coated with insulating resin layer) is woundmultiple times around a core, coating layers are bonded to preventseparation from each other to give a winding block, and this block iscut in a desired thickness along the plane forming an angle with eachinsulated conductive wire (metal wire). However, such conventionalproduction methods require multiple winding of an insulated conductivewire, which makes it difficult to make the winding direction ofinsulated conductive wires (metal wires) uniform in a given direction inthe winding block. This in turn prevents uniform direction ofinclination of plural conductive paths in an anisotropic conductiveconnector obtained by cutting the winding block. Thus, the conductivepaths bend in various directions upon pressing the anisotropicconductive connector, which increases difference (less uniformity) inthe contact pressure with the target (circuit board, semiconductorelement etc.) in the anisotropic conductive connector, which, in somecases, results in lower connection reliability with the target. Inaddition, when the winding block is to be cut, a cutting plane is setsuch that an insulated conductive wire (metal wire) forms an angle withthe line perpendicular to the cutting plane (or setting the center lineof a block at an angle with respect to the cutter) and the block is cut.By cutting the block in this way, plural anisotropic conductiveconnector films obtained by cutting have various sizes, requiringpost-processing to unify the film size. Accordingly, an anisotropicconductive connector having a desired size cannot be producedefficiently, thus posing a problem.

[0007] In view of the above-mentioned situation, the present inventionaims at providing a production method for efficiently producing ananisotropic conductive connector having a structure wherein the centerline of plural conductive paths that penetrate in the thicknessdirection of a film substrate form an angle with the line perpendicularto the principal plane of the film substrate, which shows smallvariation in the direction of inclination (bending direction ofconductive paths) among plural conductive paths, and which has highreliability of connection with a target.

[0008] In addition, the present invention aims at providing a productionmethod for efficiently producing an anisotropic conductive connectorwhich shows small variation in the direction of inclination (bendingdirection of conductive paths) among plural conductive paths, and whichhas high reliability of connection with a target, in a desired filmsize.

SUMMARY OF THE INVENTION

[0009] With the aims of achieving the above-mentioned objects, thepresent invention has the following characteristics. (1) A method ofproducing an anisotropic conductive connector having a structure whereinthe center line of plural conductive paths penetrating in the thicknessdirection of a film substrate forms an angle with a line perpendicularto the principal plane of the film substrate, which comprises the stepsof

[0010] winding an insulating film around the circumference of a core,

[0011] then helically winding a conductive wire around the circumferenceof the insulating film at a predetermined pitch, or helically winding aconductive wire around the circumference of the core,

[0012] then winding the insulating film to cover the conductive wire,

[0013] heating and pressurizing to integrate the insulating film and theconductive wire on the core to give a roll-like product,

[0014] removing the aforementioned roll-like product from the core,

[0015] incising the product to give a plane-like product,

[0016] cutting out plural films with conductive wires from theplane-like product,

[0017] then laminating the plural films with conductive wires such thatthe conductive wires on the adjacent films are parallel to each other togive a laminate,

[0018] heating and pressurizing the laminate to form a block integratingthe plural films with conductive wires, and

[0019] then cutting the block in a predetermined film thickness alongthe plane forming an angle with the conductive wire to give ananisotropic conductive connector.

[0020] (2) The production method of the above-mentioned (1), wherein theplural films with conductive wires are cut out in such a manner that theprincipal plane of the insulating film has a linear side and the centerline of the plural conductive wires forms a predetermined inclinationangle with a linear side, the plural films with conductive wires arelaminated such that the linear sides of the adjacent insulating filmsare in parallel relation, thereby forming a laminate, and a blockobtained from the laminate is cut in a predetermined film thicknessalong the plane perpendicular to a linear edge side thereof derived fromthe linear side of the principal plane of the insulating film. (3) Theproduction method of the above-mentioned (1) or (2), wherein theinsulating film and the conductive wires wound around the core are settogether with the core in a space permitting formation of adecompression or vacuum and, after decompressing or vacuumizing thespace, heated and pressurized to integrate the insulating film and theconductive wire on the core.

[0021] (4) The production method of the above-mentioned (3), wherein theaforementioned space permitting formation of a decompression or vacuumis an inner space of a bag made of a flexible film.

[0022] (5) The production method of the above-mentioned (3) or (4),wherein the aforementioned pressing is done by introducing a compressedair into the aforementioned space permitting formation of adecompression or vacuum.

[0023] (6) The production method of any of the above-mentioned (1) to(5), wherein the laminate is set in the space permitting formation of adecompression or vacuum, and after decompressing or vacuumizing thespace, heated and pressurized.

[0024] (7) The production method of the above-mentioned (6), wherein thespace permitting formation of a decompression or vacuum is an innerspace of a bag made of a flexible film.

[0025] (8) The production method of the above-mentioned (6), wherein thelaminate is housed in a heat resistant box having a size leaving someclearance between the inside surface of the box and the lateral surfaceof the laminate upon accommodation of the laminate, set in the spaceinside the bag made of a flexible film together with the heat resistantbox, and after decompressing or vacuumizing the space, heated andpressurized.

[0026] In the present specification, the “principal plane of filmsubstrate” means the surfaces of the both ends in the thicknessdirection of a film substrate, and the “principal plane of theinsulating film” means the surfaces of the both ends in the thicknessdirection of an insulating film. A reference to “a surface of a filmsubstrate” and “a surface of an insulating film” means “the principalplane of a film substrate” and “the principal plane of an insulatingfilm”, unless particularly specified.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027]FIG. 1 is a perspective view (FIG. 1(a)) of winding an insulatingfilm around a core in step 1 of the present invention, and a perspectiveview (FIG. 1(b)) of a wound product obtained by such step.

[0028]FIG. 2 is a plane view of a plane-like product obtained bydeveloping a roll-like product integrating insulating films andconductive wires.

[0029]FIG. 3(a) and FIG. 3(b) are plane views of plural films withconductive wires obtained by cutting the plane-like product.

[0030]FIG. 4 includes a perspective view (FIG. 4(a)), a sectional view(FIG. 4(b)) and a plane view (FIG. 4(c)) of a film with conductivewires.

[0031]FIG. 5 is a perspective view showing an accumulation work of filmswith conductive wires (FIG. 4).

[0032]FIG. 6 is a perspective view of a laminate obtained byaccumulating films with conductive wires (FIG. 4).

[0033]FIG. 7 is a perspective view of a block integrating laminate (FIG.6) by heating and pressurizing.

[0034]FIG. 8 is a perspective view of a step of cutting a film from theblock (FIG. 7).

[0035]FIG. 9 is a perspective view of a step of placing a laminate (FIG.6) into a heat resistant box.

[0036]FIG. 10 is a perspective view of a state wherein the laminate(FIG. 6) is housed in the heat resistant box.

[0037]FIG. 11 is a plane view (FIG. 11(a)) and a sectional view (FIG.11(b)) of the anisotropic conductive connector produced by the presentinvention.

[0038] In the Figures, the symbol 1 shows an insulating film, the symbol1 a shows the principal plane of the insulating film, the symbol 2 showsa conductive wire, the symbol L1 shows the center line of a conductivewire, the symbol L2 shows the linear side, the symbol α1 shows aninclination angle, and the symbol 10A and the symbol 10B show a filmwith conductive wires.

DETAILED DESCRIPTION OF THE INVENTION

[0039] The present invention is explained in detail in the following byreferring to the drawings.

[0040] The anisotropic conductive connector produced by the presentinvention is shown in FIG. 11(a) and FIG. 11(b), which is an anisotropicconductive connector 60 having a structure wherein plural conductivepaths 51 penetrating in the thickness direction (direction of arrow A inFIG. 11(b)) of a film substrate 50 are set such that the center line L10thereof forms an angle (α) with the line L20 perpendicular to theprincipal plane 50 a (and 50 b) of the film substrate 50. Here, FIG.11(a) is a plane view and FIG. 11(b) is a sectional view along the lineXIb-XIb in FIG. 11(a). In the Figures, D1 and D2 are pitches of theconductive paths 51 in the first and second perpendicular directions(direction of arrow X and the direction of arrow Y of principal plane 50a of film substrate 50) in the anisotropic conductive connector.

[0041] The angle (α) formed by (the center line L10 of) the pluralconductive paths 51 with the line L20 perpendicular to the principalplane 50 a of the film substrate 50 is preferably not less than 5degrees so that an effect of reducing the pressure to a target(electronic component, circuit board etc.) due to the bending of theconductive path 51 can be sufficiently afforded. When the angle is toolarge, positional adjustment (offset) with two targets (e.g., electroniccomponent and circuit board) to be electrically connected is necessary.Thus, the angle is preferably not more than 45 degrees.

[0042] The anisotropic conductive connector produced by the presentinvention is particularly preferable as a test connector, wherein thethickness of the film substrate 50 is generally about 20-1000 μm,preferably about 50-500 μm. The sectional shape of the conductive path(perpendicular to the center line L10) may be circle, polygon or anyother shape and is free of any particular limitation. In view of thereliability of connection with the target (terminal), it is preferably acircle. The diameter (width) thereof is preferably about 10-80 μm,particularly preferably about 12-60 μm, when the sectional shape iscircle, and when the sectional shape is polygon or any other shape, sucha diameter (width) as makes the sectional area thereof corresponding tothe area of a circle having a diameter within the above-mentioned scope,in view of the reliability of connection with the target (terminal),conductivity (impedance) of the conductive path itself and the like. Thepitches in the conductive path 51 (D1 and D2 in the Figures) are eachgenerally preferably 20-200 μm, particularly preferably 20-150 μm, fromthe reliability of connection with a target (terminal) and deformability(flexibility) of the anisotropic conductive connector.

[0043] The present invention relates to a method of producing ananisotropic conductive connector 60 having a structure wherein (thecenter line L10 of) plural conductive paths 51 is set to form an anglewith the line L20 perpendicular to the principal plane 50 a of the filmsubstrate 50 (a structure wherein plural conductive paths penetrate inthe thickness direction of a film substrate and the plural conductivepaths are inclined in a predetermined direction at a predeterminedangle). Basically, it includes Step 1 (step for forming plural-filmswith conductive wires), Step 2 (step for forming a block integratingplural films with conductive wires) and Step 3 (block cutting step) tobe explained in the following.

Step 1 (Step for Forming Plural Films with Conductive Wires)

[0044] As shown in FIG. 1(a), an insulating film 1 is wound around thecircumference of a core 4, then one conductive wire 2 is helically woundat a predetermined pitch around the circumference of insulating film 1(or conversely, one conductive wire 2 is helically wound at apredetermined pitch around the circumference of a core 4, and then aninsulating film 1 is wound to cover the conductive wire 2) to form awound product 5 (FIG. 1(b)). The winding here can be done using a knownwinding machine such as a horizontal type regularly winding machine andthe like. Then the wound product 5 (FIG. 1(b)) is heated and pressurizedto integrate the insulating film 1 and the conductive wire 2 on the core4 to give a roll-like product. Then the roll-like product integratingthe insulating film 1 and the conductive wire 2 is removed from the core4, a part of the roll-like product is cut to open into a plane-likeproduct 6 (FIG. 2), which is then cut to give plural films withconductive wires.

[0045]FIG. 3(a) and FIG. 3(b) show embodiment of the plural films withconductive wires. The film with conductive wires 10A shown in FIG. 3(a)is cut out from the plane-like product 6 (FIG. 2) such that theprincipal plane 1 a of the insulating film 1 is rectangular, and thedirection of (the center line of) the conductive wire 2 has aninclination toward the predetermined one side (linear side) of therectangular principal plane 1 a of the insulating film 1, and a filmwith conductive wires 10B of FIG. 3(b) is cut out from the plane-likeproduct 6 (FIG. 2) such that the principal plane la of the insulatingfilm 1 is rectangular and the direction of (the center line of) theconductive wire 2 is parallel and perpendicular to the sides (4 sides)of the rectangular principal plane 1 a of the insulating film 1. Thedouble-dotted line in FIG. 2 shows the cutting line of the film withconductive wires 10A of FIG. 3(a).

[0046] The film with conductive wires 10A of the above-mentioned FIG.3(a) intends to previously set the angle (α) formed by (the center lineL10 of) the conductive path 51 with the line L20 perpendicular to theprincipal plane 50 a of the film substrate 50 in the anisotropicconductive connector 60 (FIG. 11) to be finally produced by defining theinclination angle (inclination angle (α1) relative to the predeterminedlinear side in the principal plane 1 a of the insulating film 1) of (thecenter line of) the conductive wire 2 in the film with conductive wires10A. By the use of the film with conductive wires 10A, anisotropicconductive connector 60 (FIG. 11) wherein plural conductive paths 51 areinclined at an angle (α), can be obtained by merely cutting the blockalong the plane perpendicular to the predetermined linear edge side (oneside derived from the linear side of the principal plane 1 a of theinsulating film 1) in a later Step 3 (step for cutting the blockintegrating plural films with conductive wires).

[0047] In contrast, when a film with conductive wires 10B of FIG. 3(b)is used, an anisotropic conductive connector 60 (FIG. 11), whereinplural conductive paths 51 are inclined at an angle α, can be obtainedby setting a cutting plane such that (the center line of) the conductivewire 2 forms the aforementioned angle (α) with the line perpendicular tocutting plane, when cutting the block in a later Step 3.

[0048]FIG. 4 is an enlarged view of the above-mentioned film withconductive wires 10A (FIG. 4(a) is a perspective view, FIG. 4(b) is asectional view and FIG.4 (c) is a plane view). In the film withconductive wires 10A, plural conductive wires 2 arranged in parallel toeach other at a predetermined pitch (d2) are adhered onto therectangular principal plane 1 a of the insulating film 1, and (eachcenter line L1 of) the plural conductive wires 2 form a predeterminedinclination angle (α1) with the predetermined linear side L2 of theprincipal plane 1 a of the insulating film 1, and are positioned inparallel to the principal plane 1 a. As used herein, by the “form apredetermined inclination angle (α1)” is meant that the center line L1of the conductive wire and the linear side L2 cross at the predeterminedacute angle (α1) as shown in FIG. 4(c) (i.e., not perpendicularintersection or parallel), when the principal plane 1 a of theinsulating film is seen from the vertical above. The predeterminedinclination angle (α1) is, as explained above, corresponds to the angle(α) formed by (the center line L10 of) the conductive path 51 with theline L20 perpendicular to the principal plane 50 a (50 b) of the filmsubstrate 50 in the anisotropic conductive connector (FIG. 11) to beproduced.

[0049] The insulating film 1 constitutes the film substrate 50 of theanisotropic conductive connector 60 (FIG. 11). Accordingly, the materialof the insulating film 1 is a known material conventionally used for afilm substrate of anisotropic conductive connectors. That is, a materialthat shows adhesive property as it is, or a material that does not showan adhesive property as it is but is capable of adhesion by at leastpressurizing or heating. Examples thereof include thermoplastic orthermosetting resins such as thermoplastic polyimide resin, epoxy resin,polyetherimide resin, polyamide resin, silicone resin, phenoxy resin,acrylic resin, polycarbodiimide resin, fluorocarbon resin, polyesterresin, polyurethane resin and the like; thermoplastic elastomers such asthermoplastic polyurethane elastomer, thermoplastic polyester elastomer,thermoplastic polyamide elastomer and the like; and the like. Theseresins and elastomers may be used alone or in combination of two or morekinds thereof. These resins and elastomers may contain various materialssuch as filler, plasticizer and rubber material. Examples of the fillerinclude SiO₂ and Al₂O₃, examples of the plasticizer include TCP(tricresyl phosphate) and DOP (dioctyl phthalate), examples of therubber material include NBS (acrylonitrile-butadiene rubber), SBS(polystyrene-polybutylene-polystyrene) and the like.

[0050] The thickness of the insulating film 1 is a major factor thatdetermines the pitch of one direction (pitch (D1) in the first directionin FIG. 11) in the film substrate of the conductive path of theanisotropic conductive connector, which is generally about 20-200 μm,preferably about 20-150 μm.

[0051] The conductive wire 2 constitutes the conductive path 51 of theanisotropic conductive connector 60 (FIG. 11). For the conductive wire2, a wire-like product made of a conductive 15 material, or a wire-likeproduct made of a conductive material, which is coated with aninsulating material and which is what is called an insulated conductivewire, is used. As the wire-like product made of a conductive material, ametal wire made of at least one kind of metal (including alloy) selectedfrom gold, copper, aluminum, stainless steel, nickel and the like isused in view of the electric conductivity, and when an insulatedconductive wire is used, the material used for coating is exemplified bythose shown as examples of the materials of the above-mentionedinsulating film 1.

[0052] The sectional shape of the wire-like product made of a conductivematerial corresponds to the sectional shape of the aforementionedconductive path and may be circle, polygon or any other shape and is notparticularly limited. However, circle is preferable. The diameter(width) of the wire-like product corresponds to the diameter (width) ofthe aforementioned conductive path. When the sectional shape is circle,the diameter is preferably about 10-80 μm, particularly preferably about12-60 μm. When the sectional shape is polygon or any other shape, thesectional area is preferably the same as the area of the circle having adiameter in the above-mentioned range. The thickness of the insulatingcoating when an insulated conductive wire is used is generally about0.5-10 μm, preferably about 1-5 μm, in view of the ensured insulationproperty between conductors (wire-like products), adhesion to aninsulating film, handling property of the insulated conductive wire(workability of winding to be mentioned below) and the like.

[0053] The positional intervals (pitch (d2) in FIG. 4(b) and FIG. 4(c))between conductive wires 2 on the principal plane la of the insulatingfilm 1 of a film with conductive wires corresponds to the pitch betweenadjacent conductive paths (pitch (D2) in the second direction in FIG.11) in the film substrate in the conductive path in the anisotropicconductive connector 60 (FIG. 11), and determined as appropriate withinthe range of the aforementioned D2.

[0054] The heating temperature and applied pressure for heating andpressurizing for integrating the insulating film 1 and the conductivewire 2 on the core 4 in Step 1 vary depending on the materialconstituting the conductive wire 2 and insulating film 1 (when aninsulated conductive wire is used as a conductive wire 2, the conductivewire 2 easily adheres to the insulating film 1). The heating temperatureis generally about 50-250° C., preferably about 100-200° C. The appliedpressure is generally about 2-30 kgf/cm², preferably about 3-20 kgf/cm².

[0055] It is preferable to wind an insulating film 1 and a conductivewire 2 around the core 4 to give a wound product 5 (FIG. 1(b)), which isplaced as it is (namely, insulating film 1 and conductive wire 2together with the core 4) in a space permitting formation of adecompression or vacuum, and after decompressing or vacuumizing thespace, heated and pressurized. That is, by placing the wound product 5(FIG. 1(b)) under decompression or in vacuo before heating andpressurizing, the gap among core 4, insulating film 1 and conductivewire 2 can be effectively decreased, which in turn improves thedurability (retention of the conductive paths) of the producedanisotropic conductive connector. As used herein, the decompressionmeans a pressure smaller than the atmospheric pressure and is generallynot more than 0.06 MPa, and vacuum means decompression particularly tothe pressure of not more than 0.001 MPa. For efficient removal of thegap, the heating and pressurizing is more preferably applied in vacuo.While the method for decompression or vacuumization is not particularlylimited, suction using a pump (vacuum pump) is preferable forworkability.

[0056] The above-mentioned space permitting formation of a decompressionor vacuum is, for example, the space inside a rigid bag (i.e., boxhaving rigidity capable of retaining the shape without deformation whendecompressed or vacuumized), the space inside a bag made of a flexiblefilm and the like. The material of the rigid box is, for example, metalssuch as steel, aluminum, stainless steel, carbon steel, bronze and thelike, plastic such as polyethylene, polyurethane, acrylic resin,polyamide, polycarbonate and the like, and the like. As the flexiblefilm, a metal film such as aluminum and the like, plastic film such asnylon film, polyester film, polyethylene film, polyimide film and thelike or a laminate film wherein an aluminum film and the like arelaminated on a polyethylene film and the like, and the like can be used.

[0057] When a bag made of a flexible film is used and the space insidethe bag is vacuumized, the bag closely adheres to the wound product 5,whereby more effectively removing the gap.

[0058] In pressurizing for achieving the heating and pressurizing, auniform pressure is preferably applied to a core so that the windingstate (pitch, winding direction etc.) of the conductive wire may not bedisturbed. For this reason, a method including introducing a compressedair into the above-mentioned space (space permitting formation of adecompression or vacuum) is preferably employed. In the case of themethod including introduction of compressed air, the use of an inert gassuch as nitrogen gas and the like as the compressed air preferablyenables suppression of oxidization of the conductive wire.

Step 2 (Step for Forming a Block Integrating Plural Films withConductive Wires)

[0059] In the Step 2, plural films with conductive wires, which havebeen prepared in the aforementioned Step 1, are layered such that theconductive wires 2 of the adjacent films are in parallel relation togive a laminate, which is then heated and pressurized to form a blockintegrating plural films with conductive wires. The heating andpressurizing is a treatment for welding at least an insulating film witha conductive wire between adjacent films with conductive wires.Preferably, the insulating film is welded with the conductive wires andheating and pressurizing are applied to weld-adhering the insulatingfilms.

[0060] In the above-mentioned heating and pressurizing treatment, theheating temperature is generally within the range of from the softeningtemperature of resin (elastomer) constituting the insulating film toabout 300° C. (specifically, 50-300° C.). When a thermosetting resin isused as the insulating film 1, heating at a temperature lower than thesetting temperature is preferable. The applied pressure is generallyabout 0.49-2.94 MPa, preferably about 0.49-1.96 MPa.

[0061]FIG. 5-FIG. 7 show a manner wherein films with conductive wires10A (FIG. 3(a), FIG. 4), wherein (the center line L1 of) theaforementioned plural conductive wires 2 are inclined at an angle (α1)with the predetermined linear side L2 of the principal plane 1 a of theinsulating film 1, are accumulated (FIG. 5), such that the linear sidesL2 of the adjacent insulating films 1 are in parallel relation, and thethus-obtained laminate 20 (FIG. 6) is subjected to heating andpressurizing to form a block 30 (FIG. 7).

[0062] In the present invention, plural films with conductive wires 10Aare integrated in Step 2, and a block 30 having a structure wherein aninsulating resin R is disposed between plural conductive wires 2provided in parallel to each other in the vertical (direction ofaccumulation) and horizontal direction is formed, as shown in FIG. 7.

[0063] In the block, the interval of the conductive wire 2 (d1 in FIG.7) with regard to the direction (direction of arrow B2 in FIG. 7)corresponding to the direction of accumulation (direction of arrow B1 inFIG. 6) of the films with conductive wires 10A corresponds to the pitchin one direction (pitch (D1) in first direction in FIG. 11) in the filmsubstrate of the conductive path 51 of the anisotropic conductiveconnector 60 (FIG. 11). That is, the pitch (D1 in FIG. 11) in onedirection (first direction) in the film substrate of the conductive path51 of the anisotropic conductive connector 60 (FIG. 11) is determinedaccording to the thickness of the insulating film 1 (total of thethickness of the insulating film 1 and the thickness of the coatinglayer due to the insulating resin of the insulated conductive wire wheninsulated conductive wire is used as the conductive wire 2) and theconditions of heating and pressurizing treatment in Step 2 (temperature,pressure).

[0064] In Step 2, a laminate comprising plural films with conductivewires is heated and pressurized to give a block integrating plural filmswith conductive wires. In Step 2, too, in the same manner as in theabove-mentioned step 1, prior to heating and pressurizing, a laminatecomprising plural films with conductive wires is preferably set in aspace permitting formation of a decompression or vacuum and afterdecompressing or vacuumizing the space, heated and pressurized. In thisway, the gap between films with conductive wires vertically laminatedcan be removed, and when the gap remains in a film with conductivewires, such gap can be preferably removed. As used herein, thedecompress and vacuum mean the same as in the aforementioned step 1, andas the space permitting formation of a decompression or vacuum, thespace inside the aforementioned rigid box or the space inside a bag madeof a flexible film can be used. The method for achieving decompressionor vacuum is not particularly limited but the aforementioned suctionusing a pump is preferable from the workability. In Step 2, a bag madeof a flexible film is preferably used to achieve decompression orvacuum, in the same manner as in the aforementioned Step 1. When a bagmade of a flexible film is used, the bag closely adheres to the laminateupon vacuumization of the space inside the bag, and the gap between theaccumulated films with conductive wires can be more effectively removed.

[0065] More preferable results can be obtained when the heating andpressurizing treatment in Step 2 is conducted in the following manner.That is, as shown in FIGS. 9 and 10, laminate 20 is housed in a box 40,which is a heat resistant box having a size leaving some clearancebetween the inside surface and the laminate 20 upon accommodation of thelaminate 20 and an opening 41 for entry of the laminate 20, and in thisstate (as shown in FIG. 10), laminate 20 is set in the space inside theaforementioned bag made of a flexible film together with the heatresistant box 40, and after decompressing or vacuumizing the space,heated and pressurized. In this way, the plural films with conductivewires 10A constituting the laminate 20 can be prevented from being outof position during pressing and the direction of inclination andinclination angle of the plural conductive wires (conductive paths) ofthe anisotropic conductive connector to be produced become more uniform.By the above-mentioned leaving “some clearance” is meant a clearance ofabout 0.5-20 mm between the lateral surface of the laminate and theinside surface of the box. The “heat resistance” of the heat resistantbox means absence of deformation or softening (melting) during theabove-mentioned heat treatment, and examples of the above-mentioned heatresistant box include a metal box made of aluminum (hereinafter also tobe simply referred to as “alumi”, steel, stainless steel and the likeand a ceramic box.

Step 3 (Step for Cutting Block)

[0066] In this Step 3, the block prepared in the aforementioned Step 2is cut along the plane forming an angle with conductive wire in apredetermined film thickness to give an anisotropic conductiveconnector. FIG. 8 shows an embodiment in which block 30 (FIG. 7)obtained by accumulating films with conductive wires 10A (FIG. 3(a),FIG. 4) wherein (the center line L1 of) the aforementioned conductivewire 2 is inclined at an angle (α1) with the linear side L2 of theprincipal plane 1 a of the insulating film 1.

[0067] In FIG. 8, the cutting tool 3 is a cutter. However, as long as afilm can be cut out from a block in this step, it is not limited to acutter, but various cutting tools (wire saw, slicer, plane, laser etc.)can be used.

[0068] In the embodiment shown in FIG. 8, block 30 is cut along theplane 30 b as the cutting plane, which plane 30 b is perpendicular tothe predetermined linear edge side L2′ derived from the predeterminedlinear side L2 (see FIG. 4-FIG. 6) of the principal plane 1 a of theinsulating film 1 in the film with conductive wires in the block 30.That is, as the film with conductive wires, a film with conductive wires10A (FIG. 3(a), FIG. 4) wherein (the center line L1 of) the conductivewire 2 is inclined at an angle (α1) to the predetermined linear side L2of the principal plane 1 a of the insulating film 1, is used, and theblock 30 is cut along the plane 30 b as a cutting plane, which plane 30b is perpendicular to the linear edge side L2′ of the block 30 as thestandard, which is derived from the predetermined linear side L2 of theprincipal plane 1 a of the insulating film 1. As a result, theinclination angle (inclination angle (α1) of the center line L1 of theconductive wire 2 relative to the predetermined linear side L2 of theprincipal plane 1 a of the insulating film 1) of the conductive wire 2set for a film with conductive wires 10A directly becomes an angle (α)formed by (the center line L10 of) the conductive path 51 with the lineL20 perpendicular to the principal plane 50 a of the film substrate 50in the anisotropic conductive connector 60 (FIG. 11) to be produced.Accordingly, determination of the cutting plane in the cutting step iseasy, and an anisotropic conductive connector, wherein plural conductivepaths are inclined at the objective inclination angle and the directionsof inclination between plural conductive paths have high uniformity(plural conductive paths are inclined at a constant direction), can becertainly produced. In addition, because the size of the film (productsize) obtained by cutting is unified, obliterating the problem ofdrastic fall in the yield.

[0069] In contrast, when an anisotropic conductive connector is cut outas a film with conductive wires from a block prepared using a filmwherein (the center line of) the conductive wire is not inclinedrelative to the linear side of the principal plane of the insulatingfilm, such as a film with conductive wires 10B (FIG. 3(b)), the cuttingplane is determined such that the angle formed by (the center line of)the conductive wire with the line perpendicular to the cutting planeequals the angle (α) formed by (the center line L10) of the conductivepath 51 with the line L20 perpendicular to the principal plane 50 a ofthe film substrate 50 in the anisotropic conductive connector 60 (FIG.11).

[0070] According to the production method of the present invention, ananisotropic conductive connector is cut out from a block accumulatingplural films with conductive wires (each being substantially the samefilms cut out from a large-sized film with conductive wires) comprising(rows of) plural conductive wires arranged in parallel at the same pitchas mentioned above. As a result, a problem of non-uniform direction ofinclination of conductive paths in an anisotropic conductive connectordue to the non-uniform winding direction of insulated conductive wires(metal wires) in a conventional winding block obtained by windinginsulated conductive wires in multiplicity can be prevented, and pluralconductive paths inclined at a predetermined inclination angle, and ananisotropic conductive connector having only a small dispersion in thedirections of inclination between plural conductive paths can beproduced easily. In addition, conventionally-needed cutting whileadjusting the positions of the block and a cutter in consideration ofthe direction of (the center line of) wires in a block andpost-processing for unifying the film size (product size) of theanisotropic conductive connector cut out after the cutting are notnecessary, thereby obliterating complicated production work.Accordingly, an anisotropic conductive connector having high reliabilityof connection with a target (circuit board, semiconductor element) andin a desired size (film size (product size)) can be produced in a highyield.

[0071] While the foregoing explains the production method of the presentinvention by reference to a film with conductive wires having arectangular outer shape of the insulating film (outer shape of principalplane), the outer shape of the insulating film of a film with conductivewires in the present invention may be other than rectangular. As isunderstood from the above explanation, it is needless to say that theprincipal plane of the insulating film of a film with conductive wireshas a shape ((outer shape) having a linear side, based on which theinclination angle of the conductive wire can be defined, such asrectangular, is preferable.

[0072] Furthermore, since an anisotropic conductive connector having arectangular whole shape (outer shape of film substrate) is often used inits general applications (connector for mounting, test connector(particularly test connector)), in the present invention, too, the outershape of the insulating film of a film with conductive wires ispreferably made rectangular, so that a rectangular anisotropicconductive connector can be obtained by merely cutting the block.

[0073] In the foregoing descriptions, the production method of thepresent invention has been explained by referring to the anisotropicconductive connector 60 wherein the conductive paths 51 are arranged toform a square matrix as shown in FIG. 11. When an anisotropic conductiveconnector wherein the conductive paths are close packed is to beproduced, the films are laminated such that respective conductive wireson the film with conductive wires for odd-numbered accumulation fit intothe gaps between conductive wires on a film with conductive wires foreven-numbered accumulation, during production of a laminate comprising afilm with conductive wires.

[0074] In the present invention, moreover, when an anisotropicconductive connector of the type where the end of the entire conductivepaths or particular part of the conductive paths protrude(s) from orcave(s) into the principal plane of the film substrate, or of the typewhere only one end or both ends of each conductive path protrude from orcave into the principal plane of the film substrate is to be produced,the following treatments are conducted after the aforementioned Steps1-3.

[0075] When the end of a conductive path is protruded from the principalplane of the film substrate, a method for selectively removing theperiphery of the end of the conductive path of the film substrate to beprotruded is exemplified. To be specific, wet etching with organicsolvent, dry etching by plasma etching, argon ion laser, KrF excimerlaser and the like, and the like are used alone or in combination. Theabove-mentioned organic solvent is appropriately selected from thematerials of the coating layer of the film substrate and insulatedconductive wire. For example, dimethylacetamide, dioxane,tetrahydrofuran, methylene chloride and the like can be exemplified.

[0076] It is also possible to make protrusion by plating and depositionby precipitating of metal on the end (edge face) of the conductive pathfrom which to protrude. When a metal is precipitated, the metal may bethe same or different from the metal constituting the aforementionedconductive path. Preferable examples thereof include an Ni/Au layer byelectroless plating. By forming an Ni/Au layer by electroless plating,the contact resistance with the terminal of the target (electroniccomponent, circuit board etc.) can be advantageously suppressed to a lowlevel.

[0077] As a method for forming a recess in the conductive path from thesurface of the film substrate, a method for selectively removing onlythe conductive path exposing from the surface of the film substrate isemployed, which is specifically chemical etching with acid or alkaline.

[0078] The amount of protrusion (height from the principal plane of thefilm substrate to the tip surface of the conductive path) of theconductive path is generally selected from the range of 5-60 μm.

[0079] The anisotropic conductive connector produced by the method ofthe present invention is particularly preferable as a test connector,and for this use, the modulus of elasticity of the connector as a wholeis preferably 5-100 MPa at 0-50° C., particularly preferably 5-70 MPa.The modulus of elasticity of the connector as a whole is measured usinga dynamic viscoelasticity measure apparatus (DMS210, Seiko InstrumentsInc.). The measurement conditions are an extension mode relative to onedirection from among the directions that the surface of the filmsubstrate of the anisotropic conductive connector expands at a constantfrequency (10 Hz) at a temperature raise rate of 5° C./min and themeasurement at −30° C.-250° C. The thickness of the sample to be inputfor measurement is thickness (symbol T in FIG. 11) of the film substratein the anisotropic conductive connector 60 (FIG. 11).

[0080] The factors determining the modulus of elasticity of theconnector as a whole of the anisotropic conductive connector 60 (FIG.11) are material, width (diameter), sectional shape, inclination angleand pitch of the conductive path 51, as well as material and thicknessof the film substrate and the like. According to the production methodof the anisotropic conductive connector of the present invention,therefore, these values are controlled and the modulus of elasticity ofthe connector as a whole of the obtained anisotropic conductiveconnector for the above-mentioned measurement at −30° C. to 250° C. ispreferably set for 5-70 MPa at 0-50° C.

EXAMPLES

[0081] The present invention is explained in detail by referring toExample and Comparative Example.

Example 1

[0082] An aluminum cylindrical core having a diameter of 320 mm and alength of 270 mm is set on a horizontal type regular winding machine(HPW-02, Nittoku Engineering Co., Ltd.), on which a 50 μm-thickfluorocarbon resin film as a slip film and one layer consisting of a 100μm-thick thermoplastic polyurethane elastomer having a hardness of 75degrees (Esmer URS, Nihon Matai Co., Ltd., softening temperature 60° C.)thereon are wound, and a heat-resistant polyurethane coated wire (copperwire (diameter 25 μm) coated with heat resistant polyurethane in 2 μmthickness) having a diameter of 29 μm was wound 250 mm at a windingintervals (pitch) of 100 μm. As a slip film, a 50 μm-thick fluorocarbonresin film was wound to cover the wound wire, and on the outsidethereof, a 1 mm thick aluminum plate was set as a support plate alongthe cylindrical shape of the core.

[0083] A bag permitting formation of a vacuum space was prepared from a80 μm-thick heat resistant nylon film (1000 mm×1530 mm, WL8400-003-60-1000-SHT9, Airtec Co., Ltd., softening temperature: 220° C.)and a seal tape GS213 (Airtec Co., Ltd.), and the above-mentioned woundproduct consisting of a core, a film and a wire and a support plate inintegration was placed in this bag. The film space was hermeticallysealed and sucked with a vacuum hose (connected to a vacuum pump) tovacuumize the film space. While maintaining the vacuum, the bagcontaining the wound product and the support plate was placed in a heatpress treatable autoclave (Ashida Co., Ltd.). After setting, the insideof the tube was heated to make the temperature of the core 155° C.(temperature inside the tube: 200° C.), along with which the tube waspressed with a nitrogen gas to make the pressure inside the tube 10kgf/cm². After the core temperature and the pressure in the tube reachedthe objective levels, they were maintained for about 30 min and cooled.When the temperature reached 70° C., the pressure was released.

[0084] Thereafter, the bag containing the wound product consisting of acore, a film and a wire was taken out from the autoclave, the woundproduct was taken out from the bag to remove the core, whereby aroll-like block integrating the thermoplastic urethane elastomer filmand a heat-resistant urethane coated wire was obtained.

[0085] Then one side of the aforementioned roll-like block was cut togive a plane-like product, from which 22 films with wires were cut outusing a Thomson cutter, wherein plural heat resistant urethane coatedwires were arranged in parallel to each other at a pitch of 100 μm on aprincipal plane of a rectangular thermoplastic urethane elastomer film(120 mm×62 mm) in the state shown in FIG. 4(c), namely, the plural heatresistant urethane coated wires were arranged and adhered at aninclination angle (α1) of 15 degrees relative to the linear side L2 ofthe thermoplastic urethane elastomer film. Then the 22 films with wireswere accumulated in the vertical direction, as shown in FIG. 5, and thislaminate was placed in an aluminum box, as shown in FIGS. 9 and 10.

[0086] As the above-mentioned aluminum box, a cuboid box as a wholehaving an opening on the upper surface, permitting entry of the laminateas it is thereinto, a depth completely accommodating the laminate andhaving a size leaving some clearance of 1.5 mm between the insidesurface thereof and the lateral surface of the laminate (side surface ofa thermoplastic urethane elastomer film).

[0087] A 10 mm-thick aluminum plate (120×62 mm) was placed into theabove-mentioned aluminum box from an opening on the upper surface of thebox and on the uppermost surface of the aforementioned laminate. In thisstate, the aluminum box containing the laminate was placed in the bagmade of a nylon film, which permits formation of a vacuum space and wasused in the above, and the film space was vacuumized. While maintainingthe vacuum, the bag was placed in a heat press treatable autoclave(Ashida Co., Ltd.). The aluminum box was heated to a temperature of 175°C. (temperature inside the tube: 200° C.), along with which the tube waspressed with a nitrogen gas, such that the pressure inside thereofbecame 15 kgf/cm². After the temperature and the pressure in the tubereached the objective levels, the inside of the tube was cooled, wherebya block integrating the laminate was formed.

[0088] The block prepared in the above was cut in a predetermined filmthickness with a wire saw (F-600, Yasunaga Corporation), such that thecutting plane relative to a predetermined linear edge side (linear edgeside derived from the linear side L2 of thermoplastic urethane elastomerfilm) of the block becomes the perpendicular direction to give 200sheets (120 mm×60 mm) of anisotropic conductive connectors having athickness of the film substrate of 100 μm.

[0089] From the 200 anisotropic conductive connectors obtained abovewere arbitrarily sampled 5 connectors, each of which was examined fordispersion in the direction of inclination and the inclination angle ofconductive paths, from the two sectional directions of the anisotropicconductive connector with a microscope (OLYMPUS OPTICAL CO., LTD.). Thatis, a first section in the direction perpendicular to the principalplane of the film substrate and a second sectioncut in parallel with theprincipal plane of the film substrate were observed with a microscope.As a result, the dispersion in the direction of inclination (dispersionin angle in the direction of inclination) of all conductive pathspresent in the section was found to be 0.15 degree, from the observationof the second section and the dispersion in inclination angle was foundto be 0.22 degree, from the observation of the first section.

Comparative Example 1

[0090] An insulated conductive wire, wherein a copper wire having adiameter of 25 μm is coated with the thermoplastic polyurethaneelastomer (2 μm thick) used in the above-mentioned Example, wasregularly wound around a square columnar plastic core (entire length(winding width) 640 mm, sectional shape 160 mm×160 mm square) with awinding machine to make a closely packed winding to give a windinghaving an average winding number of 3500 turns per one layer, and anumber of layers wound of 150 layers (thickness of layer about 12 mm).The obtained roll-like winding was pressed at 10 kgf/cm² while heatingto about 150° C. to weld a thermoplastic polyurethane elastomer, thencooled to room temperature to give a winding block integrating the woundwires. This winding block was cut in a block with a band saw along aplane forming an inclination angle of 15 degrees with the wound wire. Asa result, a 120 mm×180 mm, 10 mm-thick block prior to an anisotropicconductive film was obtained. The obtained block was cut with a wiresaw, the outer diameter size was finalized to give 2800 anisotropicconductive connectors having a size of 10 mm×120 mm and a thickness of100 μm.

[0091] From the 2800 anisotropic conductive connectors obtained abovewere arbitrarily sampled 5 connectors, each of which was examined fordispersion in the direction of inclination and the inclination angle ofconductive paths, from the two sectional directions of the anisotropicconductive connector with a microscope. As a result, the dispersion inthe direction of inclination (dispersion in angle in the direction ofinclination) was found to be 0.45 degree and the dispersion ininclination angle was found to be 0.35 degree.

[0092] Using the anisotropic conductive connectors prepared in theabove-mentioned Example 1 and Comparative Example 1, a connection test(continuity test) between electronic component described in thefollowing and a circuit board was performed.

Specification of Electronic Component for Evaluation

[0093] size of parts: 9.6 mm×7.0 mm×1.65 mm (thickness)

[0094] size of electrode: 1.0 mm×0.8 mm

[0095] number of electrodes: 12

[0096] center pitch at the position of electrode: 1.8 mm

Specification of Circuit Board for Evaluation

[0097] substrate: glass epoxy substrate (FR-4)

[0098] entire thickness including circuit pattern: 1 mm

[0099] ratio of circuit width and interval width of circuit pattern:(1.0 mm: 0.8 mm)

Evaluation Method

[0100] An anisotropic conductive connector was disposed between theabove-mentioned electronic component for evaluation and the circuitboard for evaluation, a contact load 25N was applied from the electroniccomponent side to see if all the terminals (electrodes) of theelectronic component are continued with the circuit board (namely, ifall the contact points continue). This test is repeated 10 times.

Results

[0101] When the anisotropic conductive connector of Comparative Example1 was used, all contact points were continued in 8 times out of 10 timesof the test. In contrast, when the anisotropic conductive connector ofExample 1 was used, all contact points were continued in 10 times out of10 times of the test.

[0102] From this result, it is clear that the anisotropic conductiveconnector obtained by the production method of the present inventionshows smaller dispersion in the direction of inclination (bendingdirection of conductive path) between plural conductive paths, showsfine contactability with the target, and is highly reliable inconnection.

[0103] As is clear from the above explanation, the present invention canefficiently produce an anisotropic conductive connector showing smallerdispersion in the direction of inclination (bending direction ofconductive path) between plural conductive paths, fine contactabilitywith the target, and high connection reliability. In addition, ananisotropic conductive connector capable of affording high connectionreliability with the target can be produced in a desired film size andin a high yield.

What is claimed is:
 1. A method of producing an anisotropic conductiveconnector having a structure wherein the center line of pluralconductive paths penetrating in the thickness direction of a filmsubstrate forms an angle with a line perpendicular to the principalplane of the film substrate, which comprises the steps of winding aninsulating film around the circumference of a core, then helicallywinding a conductive wire around the circumference of the insulatingfilm at a predetermined pitch, or helically winding a conductive wirearound the circumference of the core, then winding the insulating filmto cover the conductive wire, heating and pressurizing to integrate theinsulating film and the conductive wire on the core to give a roll-likeproduct, removing said roll-like product from the core, incising theproduct to give a plane-like product, cutting out plural films withconductive wires from the plane-like product, then laminating the pluralfilms with conductive wires such that the conductive wires on theadjacent films are parallel to each other to give a laminate, heatingand pressurizing the laminate to form a block integrating the pluralfilms with conductive wires, and then cutting the block in apredetermined film thickness along the plane forming an angle with theconductive wire to give an anisotropic conductive connector.
 2. Theproduction method of claim 1, wherein the plural films with conductivewires are cut out in such a manner that the principal plane of theinsulating film has a linear side and the center line of the pluralconductive wires forms a predetermined inclination angle with the linearside, the plural films with conductive wires are laminated such that thelinear sides of the adjacent insulating films are in parallel relation,thereby forming a laminate, and a block obtained from the laminate iscut in a predetermined film thickness along the plane perpendicular to alinear edge side thereof derived from the linear side of the principalplane of the insulating film.
 3. The production method of claim 1,wherein the insulating film and the conductive wires wound around thecore are set together with the core in a space permitting formation of adecompression or vacuum and, after decompressing or vacuumizing thespace, heated and pressurized to integrate the insulating film and theconductive wire on the core.
 4. The production method of claim 3,wherein said space permitting formation of a decompression or vacuum isan inner space of a bag made of a flexible film.
 5. The productionmethod of claim 3, wherein said pressing is done by introducing acompressed air into said space permitting formation of a decompressionor vacuum.
 6. The production method of claim 1, wherein the laminate isset in the space permitting formation of a decompression or vacuum, andafter decompressing or vacuumizing the space, heated and pressurized. 7.The production method of claim 6, wherein the space permitting formationof a decompression or vacuum is an inner space of a bag made of aflexible film.
 8. The production method of claim 6, wherein the laminateis housed in a heat resistant box having a size leaving some clearancebetween the inside surface of the box and the lateral surface of thelaminate upon accommodation of the laminate, set in the space inside thebag made of a flexible film together with the heat resistant box, andafter decompressing or vacuumizing the space, heated and pressurized.